clang/lib/StaticAnalyzer/Checkers/CheckObjCInstMethSignature.cpp

   1 //===-- CheckObjCInstMethSignature.cpp - Check ObjC method signatures -----===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 //  This file defines a CheckObjCInstMethSignature, a flow-insensitive check
  10 //  that determines if an Objective-C class interface incorrectly redefines
  11 //  the method signature in a subclass.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
  16 #include "clang/Analysis/PathDiagnostic.h"
  17 #include "clang/AST/ASTContext.h"
  18 #include "clang/AST/DeclObjC.h"
  19 #include "clang/AST/Type.h"
  20 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
  21 #include "clang/StaticAnalyzer/Core/Checker.h"
  22 #include "llvm/ADT/DenseMap.h"
  23 #include "llvm/Support/raw_ostream.h"
  24
  25 using namespace clang;
  26 using namespace ento;
  27
  28 static bool AreTypesCompatible(QualType Derived, QualType Ancestor,
  29                                ASTContext &C) {
  30
  31   // Right now don't compare the compatibility of pointers.  That involves
  32   // looking at subtyping relationships.  FIXME: Future patch.
  33   if (Derived->isAnyPointerType() &&  Ancestor->isAnyPointerType())
  34     return true;
  35
  36   return C.typesAreCompatible(Derived, Ancestor);
  37 }
  38
  39 static void CompareReturnTypes(const ObjCMethodDecl *MethDerived,
  40                                const ObjCMethodDecl *MethAncestor,
  41                                BugReporter &BR, ASTContext &Ctx,
  42                                const ObjCImplementationDecl *ID,
  43                                const CheckerBase *Checker) {
  44
  45   QualType ResDerived = MethDerived->getReturnType();
  46   QualType ResAncestor = MethAncestor->getReturnType();
  47
  48   if (!AreTypesCompatible(ResDerived, ResAncestor, Ctx)) {
  49     std::string sbuf;
  50     llvm::raw_string_ostream os(sbuf);
  51
  52     os << "The Objective-C class '"
  53        << *MethDerived->getClassInterface()
  54        << "', which is derived from class '"
  55        << *MethAncestor->getClassInterface()
  56        << "', defines the instance method '";
  57     MethDerived->getSelector().print(os);
  58     os << "' whose return type is '" << ResDerived
  59        << "'.  A method with the same name (same selector) is also defined in "
  60           "class '"
  61        << *MethAncestor->getClassInterface() << "' and has a return type of '"
  62        << ResAncestor
  63        << "'.  These two types are incompatible, and may result in undefined "
  64           "behavior for clients of these classes.";
  65
  66     PathDiagnosticLocation MethDLoc =
  67       PathDiagnosticLocation::createBegin(MethDerived,
  68                                           BR.getSourceManager());
  69
  70     BR.EmitBasicReport(
  71         MethDerived, Checker, "Incompatible instance method return type",
  72         categories::CoreFoundationObjectiveC, os.str(), MethDLoc);
  73   }
  74 }
  75
  76 static void CheckObjCInstMethSignature(const ObjCImplementationDecl *ID,
  77                                        BugReporter &BR,
  78                                        const CheckerBase *Checker) {
  79
  80   const ObjCInterfaceDecl *D = ID->getClassInterface();
  81   const ObjCInterfaceDecl *C = D->getSuperClass();
  82
  83   if (!C)
  84     return;
  85
  86   ASTContext &Ctx = BR.getContext();
  87
  88   // Build a DenseMap of the methods for quick querying.
  89   typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
  90   MapTy IMeths;
  91   unsigned NumMethods = 0;
  92
  93   for (auto *M : ID->instance_methods()) {
  94     IMeths[M->getSelector()] = M;
  95     ++NumMethods;
  96   }
  97
  98   // Now recurse the class hierarchy chain looking for methods with the
  99   // same signatures.
 100   while (C && NumMethods) {
 101     for (const auto *M : C->instance_methods()) {
 102       Selector S = M->getSelector();
 103
 104       MapTy::iterator MI = IMeths.find(S);
 105
 106       if (MI == IMeths.end() || MI->second == nullptr)
 107         continue;
 108
 109       --NumMethods;
 110       ObjCMethodDecl *MethDerived = MI->second;
 111       MI->second = nullptr;
 112
 113       CompareReturnTypes(MethDerived, M, BR, Ctx, ID, Checker);
 114     }
 115
 116     C = C->getSuperClass();
 117   }
 118 }
 119
 120 //===----------------------------------------------------------------------===//
 121 // ObjCMethSigsChecker
 122 //===----------------------------------------------------------------------===//
 123
 124 namespace {
 125 class ObjCMethSigsChecker : public Checker<
 126                                       check::ASTDecl<ObjCImplementationDecl> > {
 127 public:
 128   void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
 129                     BugReporter &BR) const {
 130     CheckObjCInstMethSignature(D, BR, this);
 131   }
 132 };
 133 }
 134
 135 void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
 136   mgr.registerChecker<ObjCMethSigsChecker>();
 137 }
 138
 139 bool ento::shouldRegisterObjCMethSigsChecker(const CheckerManager &mgr) {
 140   return true;
 141 }